Bombing suspect Tamerlan Tsarnaev is being investigated in a possible link to triple murders back in 2011.

Tamerlan and his brother Dzhokhar are already suspected of bombing innocent civilians at the Boston Marathon, but Tamerlan, who has since died in a police shootout during the manhunt for the suspects, is being investigated for the gruesome murders that took place in suburban Boston.

Tamerlan, 26, was a close friend of one of three that were stabbed to death in an apartment in Waltham, Mass., back in September 2011.

At the time of the murders, the Middlesex County District Attorney's office said that the victims knew their murderer(s) and that they were not random attacks.

Some previous reports suggested that Tamerlan turned radical after his best friend was murdered in the attacks, but now he is being linked after a report on Buzzfeed.com said former associates suspected that he may have been involved in their murder.

Stephanie Guyotte, a spokeswoman for the county's attorney's office said: "We are definitely going to pursue any new leads." Investigators will dig further to see whether the late suspect was involved in the crime.

Tamerlan had once introduced Brendan Mess, one of the victims murdered, as his best friend at his favorite gym, according to Boston Globe. Tamerlan and Brendan used to work out together.

Meanwhile, 19-year-old Dzhokhar has officially been charge in his hospital bed Monday with using a weapon of mass destruction. He is currently in a stable condition at Beth Israel Deaconess Medical Center but is unable to talk due to a throat injury that was self-inflicted when he pulled a gun in his mouth as he was about to be captured by police.

Dzhokhar was captured alive but in critical condition on April 19 after one of the nation's largest manhunts. He was found hiding in a boat on 76 Franklin Street in Watertown, Mass.

See a video of the bombers' uncle saying they are 'losers'.